This three-year grant supports the work of Professor Robert Panvini, a post-doctoral associate and several graduate students on the completion of the construction of the "SLD" experiment at the Stanford Linear Collider. SLD will study electron-positron annihilations at an energy of 100 Gev. The group will concentrate on the central drift chamber, event simulation and data analysis. The work supported here is on one of a new generation of experiments which will study the structure of matter at a new and shorter distance scale. The particles produced in these collisions will tell us about the validity of current theories of matter and forces, and in particular give us information on the number of "generations" of elementary particles.